The present invention relates generally to the design and construction of a gearbox for a gas turbine engine. More particularly, the present invention has one embodiment wherein the gearbox defines an inline two-stage reduction gearbox for a gas turbine turboprop engine.
Gas turbine turboprop engine designers generally couple a gear reduction gearbox with the engine in order to reduce the output shaft speed, and increase the torque delivered to an output device, such as a propeller. It is well known that gas turbine engines are high speed rotary equipment having components including an output shaft revolving at speeds from about 5,000 to 50,000 revolutions per minute. Sometimes, in order to harness the power from the output shaft of the gas turbine engine a gear reduction gearbox is coupled to the engine to decrease shaft rotation speed and increase output torque. Gear reduction gearboxes include gear sets therein for reducing the shaft speed during the transmission of power from the gas turbine engine to the propeller.
The application of gas turbine turboprop engines as a propulsion means for an aircraft often creates design parameter conflicts, such as the need for a durable long life gear train and the necessity to minimize the volume and weight of the respective engine. Prior designers of gas turbine engine gear reduction gearboxes have generally used multi-stage gearboxes to effectuate significant shaft speed reduction. Even with the variety of prior gas turbine gear reduction gearboxes there remains a need for an improved gear reduction gearbox. The present invention satisfies this need in a novel and unobvious way.